The talk of preventive strikes on North Korea within the expert community has largely ended. It was never a seriously possibility. North Korea has many options to retaliate to any strike and all would come with catastrophic damage to South Korea and Japan and thereby to U.S. interests in Asia.
North Korea can be successfully deterred in the same way that all other nuclear weapon states are deterred from using their weapons. Unfortunately the National Security Advisor McMaster has not yet received that message:
STEPHANOPOULOS: But your predecessor Susan Rice wrote this week that the U.S. could tolerate nuclear weapons in North Korea the same way we tolerated nuclear weapons in the Soviet Union far more during the Cold War. Is she right?
MCMASTER: No, she's not right. And I think the reason she's not right is that the classical deterrence theory, how does that apply to a regime like the regime in North Korea? A regime that engages in unspeakable brutality against its own people? A regime that poses a continuous threat to the its neighbors in the region and now may pose a threat, direct threat, to the United States with weapons of mass destruction? A regime that imprisons and murders anyone who seems to oppose that regime, including members of his own family, using sarin nerve gase (sic) -- gas in a public airport?